Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Ashish Kumar Meena
Adi Zitrin
Yolanda Jiménez-Teja
Erik Zackrisson
Wenlei Chen
Dan Coe
Jose M. Diego
Paola Dimauro
Lukas J. Furtak
Patrick L. Kelly
Masamune Oguri
Brian Welch
Abdurro'uf
Felipe Andrade-Santos
Angela Adamo
Rachana Bhatawdekar
Maruša Bradač
Larry D. Bradley
Pratika Dayal
Megan Donahue
Abstract： We report the discovery of two extremely magnified lensed star candidates behind the galaxy cluster MACS J0647.7+7015, in recent multi-band James Webb Space Telescope (JWST) NIRCam observations. The candidates are seen in a previously known, $z_{phot}\simeq4.8$ dropout giant arc that straddles the critical curve. The candidates lie near the expected critical curve position but lack clear counter images on the other side of it, suggesting these are possibly stars undergoing caustic crossings. We present revised lensing models for the cluster, including multiply imaged galaxies newly identified in the JWST data, and use them to estimate a background macro-magnification of at least $\gtrsim90$ and $\gtrsim50$ at the positions of the two candidates, respectively. With these values, we expect effective, caustic-crossing magnifications of $10^4-10^5$ for the two star candidates. The Spectral Energy Distributions (SEDs) of the two candidates match well spectra of B-type stars with best-fit surface temperatures of $\sim10,000$ K, and $\sim12,000$ K, respectively, and we show that such stars with masses $\gtrsim20$ M$_{\odot}$ and $\gtrsim50$ M$_{\odot}$, respectively, can become sufficiently magnified to be observed. We briefly discuss other alternative explanations and conclude these are likely lensed stars, but also acknowledge that the less magnified candidate may instead be or reside in a star cluster. These star candidates constitute the second highest-redshift examples to date after Earendel at $z_{phot}\simeq6.2$, establishing further the potential of studying extremely magnified stars to high redshifts with the JWST. Planned visits including NIRSpec observations will enable a more detailed view of the candidates already in the near future.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Rogier A. Windhorst
Seth H. Cohen
Rolf A. Jansen
Jake Summers
Scott Tompkins
Christopher J. Conselice
Simon P. Driver
Haojing Yan
Dan Coe
Brenda Frye
Norman Grogin
Anton Koekemoer
Madeline A. Marshall
Rosalia O'Brien
Nor Pirzkal
Aaron Robotham
Russell E. Ryan,
Christopher N. A. Willmer
Timothy Carleton
Jose M. Diego
Abstract： We give an overview and describe the rationale, methods, and first results from NIRCam images of the JWST "Prime Extragalactic Areas for Reionization and Lensing Science" ("PEARLS") project. PEARLS uses up to eight NIRCam filters to survey several prime extragalactic survey areas: two fields at the North Ecliptic Pole (NEP); seven gravitationally lensing clusters; two high redshift proto-clusters; and the iconic backlit VV 191 galaxy system to map its dust attenuation. PEARLS also includes NIRISS spectra for one of the NEP fields and NIRSpec spectra of two high-redshift quasars. The main goal of PEARLS is to study the epoch of galaxy assembly, AGN growth, and First Light. Five fields, the JWST NEP Time-Domain Field (TDF), IRAC Dark Field (IDF), and three lensing clusters, will be observed in up to four epochs over a year. The cadence and sensitivity of the imaging data are ideally suited to find faint variable objects such as weak AGN, high-redshift supernovae, and cluster caustic transits. Both NEP fields have sightlines through our Galaxy, providing significant numbers of very faint brown dwarfs whose proper motions can be studied. Observations from the first spoke in the NEP TDF are public. This paper presents our first PEARLS observations, their NIRCam data reduction and analysis, our first object catalogs, the 0.9-4.5 $\mu$m galaxy counts and Integrated Galaxy Light. We assess the JWST sky brightness in 13 NIRCam filters, yielding our first constraints to diffuse light at 0.9-4.5 {\mu}m. PEARLS is designed to be of lasting benefit to the community.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Miriam Golubchik
Adi Zitrin
Justin Pierel
Lukas J. Furtak
Ashish K. Meena
Or Graur
Patrick L. Kelly
Dan Coe
Felipe Andrade-Santos
Maor Asif
Larry D. Bradley
Wenlei Chen
Brenda L. Frye
Sebastian Gomez
Saurabh Jha
Guillaume Mahler
Mario Nonino
Louis-Gregory Strolger
Yuanyuan Su
Abstract： The Reionization Cluster Survey (RELICS) imaged 41 galaxy clusters with the Hubble Space Telescope (HST), in order to detect lensed and high-redshift galaxies. Each cluster was imaged to about 26.5 AB mag in three optical and four near-infrared bands, taken in two distinct visits separated by varying time intervals. We make use of the multiple near-infrared epochs to search for transient sources in the cluster fields, with the primary motivation of building statistics for bright caustic crossing events in gravitational arcs. Over the whole sample, we do not find any significant ($\gtrsim5 \sigma$) caustic crossing events, in line with expectations from semi-analytic calculations but in contrast to what may be naively expected from previous detections of some bright events, or from deeper transient surveys that do find high rates of such events. Nevertheless, we find six prominent supernova (SN) candidates over the 41 fields: three of them were previously reported and three are new ones reported here for the first time. Out of the six candidates, four are likely core-collapse (CC) SNe -- three in cluster galaxies, and among which only one was known before, and one slightly behind the cluster at $z\sim0.6-0.7$. The other two are likely Ia -- both of them previously known, one probably in a cluster galaxy, and one behind it at $z\simeq2$. Our study supplies empirical bounds for the rate of caustic crossing events in galaxy cluster fields to typical HST magnitudes, and lays the groundwork for a future SN rate study.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Larry D. Bradley
Dan Coe
Gabriel Brammer
Lukas J. Furtak
Rebecca L. Larson
Felipe Andrade-Santos
Rachana Bhatawdekar
Marusa Bradac
Tom Broadhurst
Adam Carnall
Christopher J. Conselice
Jose M. Diego
Brenda Frye
Seiji Fujimoto
Tiger Y. -Y Hsiao
Taylor A. Hutchison
Intae Jung
Guillaume Mahler
Stephan McCandliss
Masamune Oguri
Abstract： JWST was designed to peer into the distant universe and study galaxies nearer the beginning of time than previously. Here we report the discovery of 12 galaxy candidates observed 300-600 Myr after the Big Bang with photometric redshifts between z ~ 8.5-13 measured using JWST NIRCam imaging of the galaxy cluster WHL0137 observed in 8 filters spanning 0.8-5.0 $\mu$m, plus 9 HST filters spanning 0.4-1.7 $\mu$m. Three of these candidates are gravitationally lensed by the foreground galaxy cluster and have magnifications of $\mu \sim 3 - 8$. The remaining nine candidates are located in a second JWST NIRCam module, centered ~29' from the cluster center, with expected magnifications of $\mu$ <~ 1.1. Our sample of high-redshift candidates have observed F200W AB magnitudes between 25.9 and 28.1 mag and intrinsic F200W AB magnitudes between 26.4 and 29.7 mag ($M_{UV}$ = -22.5 to -17). We find the stellar masses of these galaxies are in the range $\log M_{*}/M_{\odot}$ = 8 - 9, and down to 7.5 for the lensed galaxies. All are young with mass-weighted ages < 100 Myr, low dust content $A_V$ < 0.15 mag, and high specific star formation rates sSFR ~10-50 Gyr$^{-1}$ for most. One z ~ 9 candidate is consistent with an age < 5 Myr and a sSFR ~250 Gyr$^{-1}$, as inferred from a strong F444W excess, implying [OIII]+H-beta rest-frame equivalent width ~2000 Angstrom, although an older and redder z~ 10 object is also allowed. Another z~9 candidate ID9356 is lensed into an arc 2.6" long by the effects of strong gravitational lensing ($\mu$~8), and has at least two bright knots of unevenly distributed star formation. This arc is the most spatially-resolved galaxy at z~9 known to date, revealing structures ~30 pc across. Follow-up spectroscopy of WHL0137 with JWST/NIRSpec is planned for later this year, which will validate some of these candidates and study their physical properties in more detail.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Lukas J. Furtak
Ramesh Mainali
Adi Zitrin
Adèle Plat
Seiji Fujimoto
Megan Donahue
Erica J. Nelson
Franz E. Bauer
Ryosuke Uematsu
Gabriel B. Caminha
Felipe Andrade-Santos
Larry D. Bradley
Karina I. Caputi
Stéphane Charlot
Jacopo Chevallard
Dan Coe
Emma Curtis-Lake
Daniel Espada
Brenda L. Frye
Kirsten K. Knudsen
Abstract： We report the discovery of a triply-imaged active galactic nucleus (AGN), lensed by the galaxy cluster MACS J0035.4-2015 ($z_{\mathrm{d}}=0.352$). The object is detected in Hubble Space Telescope (HST) imaging taken for the RELICS program. It appears to have a quasi-stellar nucleus consistent with a point-source, with a de-magnified radius of $r_e\lesssim100$ pc. The object is spectroscopically confirmed to be an AGN at $z_{\mathrm{spec}}=2.063\pm0.005$ showing broad rest-frame UV emission lines, and is detected in both X-ray observations with \textit{Chandra} and in ALCS ALMA band 6 (1.2 mm) imaging. It has a relatively faint rest-frame UV luminosity for a quasar-like object, $M_{\mathrm{UV},1450}=-19.7\pm0.2$. The object adds to just a few quasars or other X-ray sources known to be multiply lensed by a galaxy cluster. Some faint, diffuse emission from the host galaxy is also seen around the nucleus, and nearby there is another fainter object sharing the same multiple-imaging symmetry and geometric redshift, which may be an interacting galaxy or a star-forming knot in the host. We present an accompanying lens model, calculate the magnifications and time delays, and infer physical properties for the source. We find the rest-frame UV continuum and emission lines to be dominated by the AGN, and the optical emission to be dominated by the relatively young ($\sim100$ Myr) host galaxy of modest stellar mass $M_{\star}\simeq10^{9.2} \mathrm{M}_{\odot}$. We also observe variations in the AGN's emission, which may suggest that the AGN used to be more active. This object adds a low-redshift counterpart to several relatively faint AGN recently uncovered at high redshifts with HST and JWST.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Jose M. Diego
Ashish K. Meena
Nathan J. Adams
Tom Broadhurst
Liang Dai
Dan Coe
Brenda Frye
Patrick Kelly
Anton M. Koekemoer
Massimo Pascale
S. P. Willner
Erik Zackrisson
Adi Zitrin
Rogier A. Windhorst
Seth H. Cohen
Rolf A. Jansen
Jake Summers
Scott Tompkins
Christopher J. Conselice
Simon P. Driver
Abstract： The first JWST data on the massive colliding cluster El Gordo confirm 23
known families of multiply lensed images and identify 8 new members of these
families. Based on these families, which have been confirmed spectroscopically
by MUSE, we derived an initial lens model. This model guided the identification
of 37 additional families of multiply lensed galaxies, among which 28 are
entirely new systems, and 9 were previously known. The initial lens model
determined geometric redshifts for the 37 new systems. The geometric redshifts
agree reasonably well with spectroscopic or photometric redshifts when those
are available. The geometric redshifts enable two additional models that
include all 60 families of multiply lensed galaxies spanning a redshift range
$2
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abdurro'uf
Dan Coe
Intae Jung
Henry C. Ferguson
Gabriel Brammer
Kartheik G. Iyer
Larry D. Bradley
Pratika Dayal
Rogier A. Windhorst
Adi Zitrin
Ashish Kumar Meena
Masamune Oguri
Jose M. Diego
Vasily Kokorev
Paola Dimauro
Angela Adamo
Christopher J. Conselice
Brian Welch
Eros Vanzella
Tiger Yu-Yang Hsiao
Abstract： We study the spatially resolved stellar populations of 444 galaxies at
$0.3
Peer Review Status:Awaiting Review
Hits
Hits
Downloads
Comment